It has become a requirement in the motor industry that car trunk lids, that is, the trunk or rear lid should need little or no manual effort to be opened, especially starting from the closed position. For example a person wishing to load luggage or shopping articles into the trunk of a car often has only one hand free, so that the lid has to be unlocked and lifted single-handedly. This can be a real problem for elderly or infirm persons.
In many cars nowadays the trunk lids are pivoted about a pair of four-link hinges. When the lid is closed each hinge is stowed, along with its gas strut, in a respective shallow gutter on each side of the trunk. This has the advantage that the trunk space remains unobstructed by the hinge mechanism. However, the almost horizontal attitude of the gas strut provides a poor mechanical advantage in assisting the initial opening of the lid, namely at the very position where the effective weight of the lid is greatest.
In co-pending European Patent Application No. 97303390.5 there is described and claimed a hinged mechanism for assisting the lifting of a closure hinged to a body, comprising: a hinge device permitting pivoting of the closure about the body, and a compressible strut acting between a first hinge part attachable to the body and a second hinge part attachable to the closure; wherein one end of the strut acts through a pivotal thrust member whose movement is constrained by engagement of a part thereof with plate means, at least when the two hinge parts are in close proximity with respect to each other, such as when the closure is in the lowered position, whereby during initial opening of the closure the plate means enables pivoting movement of the thrust member, due to the force of the strut, to cause a lifting movement of the closure.